Electric-contact device



A. A. KENT.

ELECTRIC CONTACT DEVICE. APPLICATION FILED SEPT-23,1916- Patentefl Nov. 1, 1921,

a 2 SHEETS-SHEET 1.

INVENTOR 1 WITNES ATTQRNEY A. A. KENT.

ELECTRIC CONTACT DEVICE. APPLICATION FILED SEPT. 23, 1916.

1,395,427; Patented N0v.1,1921a 2 SHEETSSHEET 2.

WITNESS ATTORNEY PATENT OFFICE.

ARTHUR ATWA'IER KENT, OF ROSEMON '1, PENNSYLVANIA.

ELECTRIC-CONTACT DEVICE.

Specification of Letters Patent.

Patented Nov. 1, 1921.

Application filed September 23, 1916. Serial No. 121,808.

To all whom it may concern:

Be it known that I, ARTHUR ATWATER KENT, a citizen of the United States, and a resident of Rosemont, Montgomery county, State of Pennsylvania, have invented certain new and useful Improvements in Electric-Contact Devices, of which the following is a specification.

My invention relates to contact makers such as are adapted for use in connection with the sparking circuits of internal combustion engines and more particularly to those devices above referred to in which the primary electric circuit is normally closed for the greater portion of the time and is momentarily broken and closed again to induce a spark in the secondary circuit of an induction coil of the sparking system.

In referring to the length of time that the primary circuit is normally closed and the length of time the circuit is broken, it should be borne in mind that these terms are rela tive. The contact device forming the subject matter of this invention is one which may be and normally is actuated at very high speeds. The main shaft or cam shaft of the device is adapted to be directly attached to and to be rotated at the same speed as the main shaft of an internal combustion engine, and there may be as many sparks formed during the complete revolution of the crank shaft of the engine and complete revolution of the main shaft of the contact device as there are cylinders in the engine. Thus when the device is used to produce the sparks necessary to ignite the charges in a six-cylinder engine the primary circuit may be broken six times for every revolution of the engine; and in a l2-cylinder engine there may be 12 sparks formed or produced for every revolution of the engine. It is, of course, to be understood that the number of explosions for every revolution of the crank shaft will be affected by and will vary with the character of the engine and the angles that the various cranks make with each other. It must therefore appear that inasmuch as the device is arranged to make and close a circuit three hundred or more times per second the length of time that the circuit will be closed will be, generally speaking. exceedingly short, but that length of time is much longer than the period during which the contact points are separated and closed again.

The objects of this invention are to provide a device which will positively operate to hold the circuit closed all the time except during an almost infinitesimal length of time when the contacts are separated and the spark is induced in the secondary circuit; to arrange and construct the moving parts in such a manner that the making and closing of the primary circuit will be a positive operation, and in such a manner that the contact points are only separated at the desired and predetermined points during the revolution of the engine shaft or cam shaft; to make and construct the moving parts of such small dimensions and of so light a weight'as to reduce to a minimum any undesirable effects which may be produced by the momentum of the moving parts; to arrange the device so that there will be no breaking down or jumping of the spark in either the primary or secondary circuits due to inductance during the rapid opening and closing of the contact points; to provide a device in which the extent of the movement of the actuating parts is as light as possible consistent with the proper separation of the contact points; to reduce wear of the moving parts; to provide a resistance for limiting the current in the primary circuit of the induction coil and to apply the forces utilized in moving the movable contact point away from the stationary contact point, and in returning the movable contact point into engagement with the stationary contact point; as nearly as possible, directly to the movable contact point itself, or, in other words, to the movable contact movable contact point as possible.

Other objects of my invention will appear in the specification and claims below.

Referring to the drawings formin a part of this specification, and in which t e same reference characters are employed throughout the various views to designate the same parts, Fig. 1 is a plan view of the electric contact device forming the subject matter of this specification; Fig. 2 is a similar plan view of the cover for the condenser removed and a portion of the adjustable mounting for the stationary contact point broken away; Fig. 3 is a sectional view on the line 3-3 of Fig. 1; Fig. 4.- is a sectional view of the base, cap and condenser, taken on the line 4- 1 of Fig. 1; Fig. 5 is a fragmentary plan View of the main plate or base showing point carrier as closely to the l a slightly different manner of attaching the of an internal combustion engine.

terminals of the condenser to the portions of the device provided with the movable and stationary contact points, respectively; Fig. 6 is a fragmentary sectional view on an enlarged scale taken on the line 6-6 of Fig. 1; Fig. 7 is a detailed view of the movable contact point lever and the spring attached thereto, and Fig. 8 is a bottom view of the lever and spring illustrated in Fig. 7.

In the embodiment of my invention illustrated in the drawings a base 1 is provided with a suitable bearing, 1' in which is journaled the main or cam shaft 2 adapted to be attached to and rotated with the main s lli sitlft is main shaft 2 is'provided with a cam 3 which will be provided with as many projections 4 as there are cylinders in the engine. The cam shown in the drawings is provided with six of these projections and is preferably a hexagonal cam having a very smooth peripheral surface. The projections 4 are preferably slightly rounded so as to present no cutting edge and to prevent the same from unduly abrading or wearing the cam follower arranged to cooperate with the cam 3. This cam follower is preferably a lever 5 pivoted on a screw or stud 6 to the base plate 1 and provided at its free end with a rounded edge 7 adapted to ride over the projections 4 of the cam 3 and with a similar rounded edge 8 extending in the opposite direction adapted to engage the free end of the lever 9 forming the movable contact point support or carrier. This lever 5 is preferably constructed of insulating material, or a material which is a non-conductor of electricity.

The lever 9 is preferably constructed of light sheet metalwhich is a conductor of electricity, said lever being shown in Figs. 7 and 8, and consisting of a substantially circular disk 10 having an integral. arm 11, the portion 12 of which is bent over to form a flat seat to which is secured in any suitable manner a contact point 13, preferably of tungsten or any other suitable material. The tungsten point 13 is preferably attached to the fiat portion 12 by a rivet 14, which also serves to secure one end of one or more springs 15-15 to the free end of the lever 9, said springs 15-15 being preferably provided at their opposite ends with holes or openings 1616. In the center of the disk 10 is provided a bearing stud 17 extendlng through and rigidly secured to the disk 10, and provided at its ends with conical points 18 and 19, respectively.

The support for this lever 9 is preferably a stud 20 of insulating material tightly forced into a suitable opening in the base plate 1, as clearly indicated in Fig. 6, and that portion'of the stud 2O projecting from the surfaceof the base 1 is preferably cylin- "to the base 1 by drical and its diameter is preferably the same as the diameter of the disk 10. The upper surfaceof the stud 20 is preferably provided with a circular depressed portion 21 of less diameter than the diameter of the disk 10, so that when the lever 9 is mounted thereon the disk 10 will bear against the stud 20 at its peripheral surface only as is clearly indicated in Fig. 6. The stud 20 is provided with an axially extending hole 22 of the same size as the bearing stud 17, into which the said stud is arranged to fit without bottoming.

The lever 9,-which is the movable contact point support or carrier is preferably mounted on said stud 20 in such a manner as to oscillate thereon, and is retained in operative position by a resilient arm or latch 23 pivotally secured to the stud 24, suitably secured screw threads 25, by screw or stud 26 passing through one end thereof, the free end of said arm or latch 23 being provided with an indentation 27 into which the conical point 18 of the stud 17 projects.

In this manner the movable contact point support or lever 9 is free to be oscillated about the stud 17 as an axis and is resiliently held snugly against the outer peripheral surface of the stud 20 by the resilient arm or latch 23.

Projecting from the base 1 is another stud 28 to which the free ends of the springs 15 are rigidly secured as by a screw 29 passing through the opening 16 insaid spring and threaded into the said stud 28.

Referring back to Fig. 1 the base plate 1 is preferably provided with an oblong recess 30 into which a condenser 31 is adapted to be placed, and the terminals 32 and 33 of said condenser are preferably bent backwardly over the body of the condenser so as to lie on opposite sides thereof, the lower terminal 33 resting on the metal base 1 in the bottom of the recess 30.

Over the condenser 30 is provided a cover '34 which is also preferably provided with a 1, but is electrically insulated therefrom, by

two screws 36-36. These screws 36-'-36 are exactly alike and are insulated from the base in the same manner. In Fig. 3 one of these screws and -the manner in which it is insulated is clearly illustrated. From this illustration the manner in which the second screw is secured to the parts and insulated therefrom will be readily understood without further illustration. Surrounding the screw 36 is a bushing 37 of insulating material, passing completely through the base plate 1 and projecting beyond the opposite surfaces of the base plate 1 sufficiently to project partially through washers 38 and 39, also of insulating material. The screws 36 are threaded into suitable openings 40 in the cover 34, the washer 38 lying between the cover 34 and the base 1 and the washer 39 lying between the head of the screw 36 and the base 1. Preferably a metal washer 41 is placed between the head of the screw 36 and the washer 39 of insulating material.

. Upon the top of the cover 34 is preferably mounted the support for normally stationary contact point, the same consisting of a bar or plate 42 provided at one end wih a handle or knob 43 and at its opposite end with a contact point 44 of tungsten or other suitable material, against which the movable contact point 13 is normally held pressed by the springs 15. The bar or plate 42 is preferably provided with a longitudinal slot 45 through which extend adjusting screws 46 threaded into the cover 34. When said screws 46 are tightly set the plate or bar 42 is rigidly secured to the cover 34 and when these screws are loosened the bar 42 may be moved longitudinally to bring the stationary contact point into any desired position with respect to the movable contact point 13 or, in other words, to adjust the extent of the movement of contact point 13 from the stationary contact point 44 and to aline the stationary contact point 44 with the movable point 13.

To the base plate 1 is attached a binding screw 47 by means of which the base plate may be connected to one terminal of the primary electric circuit, the wire being preferably clamped between the washer 48 and the base plate 1. A second binding screw 49 is provided, but this binding screw is insulated from the base 1 in the following manner: through an opening 50 in the base plate 1 is fitted a bushing 51 of insulating material and the ends of-this bushing project beyond the opposite sides of the base plate 1 into a washer 52 of insulating material on the top ofthe base 1 and through a washer 53 of insulating material on the under side of the base plate 1. Through this bushing 51 xtends a hollow stud 54 having a flanged head 55. This hollow stud 54 passes through the washer 52, the bushing 51, the washer 53 and through a metal washer 56 and the end is then upset to rigidly secure the said parts together with the hollow stud 54 thoroughly insulated from the base plate 1. Into this hollow stud 54 the binding screw 49 is threaded, and the other end of terminal of the primary electric circuit is preferably secured or attached to the hollow stud 54 by clamping it by the screw 49 between a metal washer 57 and the .head 55 of the hollow stud 54.

In order to limit the current in the primary circuit a resistance coil 58 (preferably of nickel) is provided and this coil 58 5 applies the force necessary is preferably clamped at one end between the washer 53 and the metal washer 56, while at its other end is preferably clamped between a metal washer 41 and a washer 39 of one of the screws 36. This is clearly illustrated in Fig. 3.

It will thus be seen that'when the binding screws 47 and 49 are attached to the terminals in a primary electric circuit, and while the contact points 13 and 44 are in engagement with each other, the circuit will be closed through binding post or screw 47, base plate 1, stud 24, arm 23, stud 17, movable contact lever 9, movable contact point 13, stationary contact point 44, bar or plate 42, cover 34, one screw 36, resistance coil 58, hollow stud 54, back to binding screw 49, and that the contact points 13 and 44 will be bridged by the condenser 31, the opposite ends of which are in electrical engagement with the cover 34 and base 1, respectively.

In Fig. 5 is illustrated a different manner of fastenin andattaching the terminals 32 and 33 of the condenser to the cover and base, respectively. Inthis construction the terminals of the condenser are made longer than that shown in F ig. 2 and the upper terminal 32' is bent longitudinally of the condenser and then at right angles so that the end of it is clamped between the washer 38 and the cover 34 by One of the screws 36. The lower terminal 33' is similarly bent to extend first lon itudinally of the condenser, and is then bent at right angles to lie between the washer 38 and the base 1 by the other screw 36.

As shown in Fig. 2 the normally stationarv contact point 44 is adjusted so that when the lever 5 is riding over the projection 4 of the cam the movable contact point 13 will be sufiiciently separated from the stationary contact point 44 to insure a proper breaking of the current. lVhen, however, the cam is revolved to bring the projection 4 out from under the rounded edge 7 of the lever 5, the spring will immediately return the contact point 13 into engagement with the contact point 4" to close the current. From the comparison of Figs. 1 and 2 it would be further seen that the time of the engagement of the lever 5 with a projection 4 of the cam 3 is relatively short as compared with the time that the contact points are in engagement with each other.

The lever 9 and the springs 15 are all of very light construction so as to have very little momentum, and 'as above set forth, they will also be seen to have very little motion to efiect a complete and positive breaking of the circuit at the proper time between the contact points. The lever to separate the contact points directly to the end of the lever 9, and thus applies it substantially 130 pressure.

directly on the contact point 13, and the springs 15 also annly their force directly on the contact point 13.

The arm or latch 23 is in fact a leaf spring, the free end of which normally presses against the conical point '18 of the stud 17, and this pressure may, of course, be varied by springing the arm 23 to produce the desired and proper amount of But the pressure of the arm 23 against the stud 17 forces the disk 10 firmly and squarely against the peripheral ring oh the stud 20 surrounding the depression 21 therein, and this pressure produces a frictional resistance to the free movement of the arm 11 about the axis of the stud 17, which friction tends to counteract or absorb the momentum of the lever 11 when being oscillated at high speeds by the cam 3 and springs 15, and prevents the cam from throwing the lever 11 and contact point 13 carried therebv further away from the contact point 44 when being operated at high speeds than it does at low speeds. This friction substantially absorbs the effect of momentum in the vibrating parts when being operated at hi h speeds, and the pressure which the spring 23 exerts is readily adjusted to effect this result.

Although I have described one form or embodiment of my invention I do not wish to be construed as being limited strictly thereto as many changes in form and arrangement of parts may be made without departing from the spirit and scope of my invention. Y

\Vhat I claim and desire to protect by Letters Patent of the United States are:

1. In a contact device the combination of a rotatable cam, a stationary contact point support, a short li ht sheet metal pivoted lever, and a movable contact point carried substantially at the free end thereof,

a spring having one end attached to the free end of said lever and acting to hold said movable contact noint against said stationary contact point, and a light lever having its free end between said cam and the free end of said lever, and operative to transmit motion from said cam directly to the free end of said lever to intermittently separate said contact points, said spring being operative to return said movable contact point into engagement with said stationary contact point while said cam is moving out of en agement with the free end of said intermediate lever.

2. In a closed circuit contact device, the combination of a stationary contact point, a movable contact point support comprising a pivoted lever carrying said movable contact point at its free end, a spring acting on the free endof said lever and tending to hold said contact points normally in engagement with each other, means to 1,ses,ea7

intermittently separate said contact points against the tension of said spring, :and

frictional means at the pivotal bearing of said lever to counteract the momentum of said lever when it is rapidly vibrated under the influence of said means to separate said contact points and said spring;

3. In a closed circuit contact device a combination with a base, a shaft journaled in said base, a cam carried by said shaft, a stationary contact point, a movable contact point, and a pivoted support for said movable contact point, said support comprising a short light metal lever carrying said movable contact point at its free end, a pivotal stud unitary with said lever, of a support mounted on said base and composed of insulating material, into which one end of said stud fits, a spring pressing against the other end of said stud and holding said lever against the upper surface of said support to provide a frictional resistance between said lever and said support tending to counteract the momentum of said lever when vibrating at relatively high speeds, a spring pressing against the free end of said lever and tending to normally hold said movable contact point against said stationary contact point, said cam being adapted to momentarily separate said contact points and said spring being operative to instantaneously return said stationary contact point the instant said cam has separated said contact points.

4. In a closed circuit contact device the combination of a base, a rotatable shaft journaled in said base, a cam secured to said shaft, a stationary contact point insulated from said base, a movable contact point support comprising a light short metal lever, a movable contact point mounted thereon, a support in which said lever is pivoted, said support being mounted on said base and being composed of insulating material, aspring mounted on said base and having its free end holding said lever against said support to produce friction between said lever and said support of insulating material, a metal spring mounted-0n said base, and having its free end pressing against the free end of said lever to normally hold said movable contact point in engagement with said stationary contact point, and an intermediate member of insulating material mounted on said base and having one end extending into the path of said cam and engaging the free end of said lever to communicate the motion .of said cam to said lever to momentarily separate said contact points;

5. In a closed circuit contact device, a

i ,eeaaav points, resilient means normally holding said contact points together to close an electrical circuit therethrough and to bring said contact points into instantaneous engagement with each other after said points have been separated by said cam, and a resistance coil mounted on and insulated from said base, electrically connected to said cover, and in series with said contact points when the circuit is closed through said points.

6. In a closed circuit contact device the combination of a base, a cam mounted to turn on said base, a movable contact point, a light pivoted lever on the end oi which said movable contact point is carried, a support for said lever, insulated from said base, a spring mounted on said base and normally pressing against the free end of said lever, an intermediate member of insulating material mounted on said base, and having its free end extending substantially between the exterior surface of said cam and the free end of said lever, a stationary contact point, a support therefor insulated from said base and means to manually adjust said stationary contact point toward and away "from said movable contact point to vary at will the length of time and the extent to which said contact points are separated by said cam through said intermediate lever.

7. In a contact device the combination of a stationary contact point, a movable contact point support comprising a pivoted lever carrying said movable contact point at its free end, means to oscillate said lever to intermittently bring said contact points into and out of engagement with each other, and frictional means to counteract the momentum of said lever when it is rapidly vibrated by said means to vibrate the same.

8. In a closed circuit device the combination of a base, a rotable shaft journaled in said base, a cam secured to said shaft, a stationary contact point insulated from said base, a movable contact point support comprising a light lever, a movable contact point mounted thereon, a support in which said lever is pivoted, a spring mounted on said base and holding said lever against said support to produce friction between said lever and said support, a spring mounted on said base and pressing against said lever to normally hold said movable contact point in engagement with said stationary contact point, and an intermediate member mounted on said base and having one end extending into the path of said cam and engaging said lever to communicate the motion of said cam to said lever to momentarily separate said contact points.

9. In a contact device a movable contact point support comprising a light rigid lever of sheet metal, a contact point rigidly mounted on the free end thereof, a leaf spring rigidly attached at one end to the free end of said lever and a pivoted stud rigidly secured to said lever, said lever having a relatively extended surface concentric with said pivoted stud afford and provide a substantial frictional bearing surface.

10. in a contact device a movable contact point support comprising a lever of sheet metal consisting substantially of a disk and an arm projecting therefrom, said arm being stitl'ened longitudinally by a flange proving a plane surface extending along an edge of said arm, a contact point and a spring rigidly secured to said flange adjacent the end of said lever and a pivotal stud rigidly secured at the center of said disk.

11. In a contact device the combination with an actuating cam and a movable contact point support, of means for transmitting motion between said operating cam and said movable contact point support comprising a lever of insulating material having a pivotal opening at one end thereof and provided at its free end with oppositely disposed projections having rounded ends providing surfaces for contacting, respectively, with an operating cam and with a movable contact point support.

In witness whereof I have hereunto set my, hand this nineteenth day of September 1916.

ARTHUR ATWATER KENT. 

